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<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        var index = 0;
        for (let index = 0; index < 10; index++) {
            console.log(index);
        }
        // while语句的表达式为
        while (index<10) {
            console.log(index);
            index++;
            
        }
    </script>
</body>

</html>